Auxiliary power operated device for machine tools



Feb. 2, 1937. A. N. EMMONS AUXILIARY POWER OPERATED DEVICE FOR MACHINE TOOLS Filed Aug. 20, 1934 5 Sheets-Sheet l ATTORNEYS- Feb. 2, 1937. N. EMMONS I 2,069,701

, AUXILIARY POWER OPERATED DEVICE FOR MACHINE TOOLS Filed Aug. 20, 1934 s Sheets-Sheet 2 INVENTOR.

wizww/ ATTORNEYS.

' Feb. 2, 1937. A. N. EMMONS 2,069,701

AUXILIARY POWER OPERATED DEVICE FOR MACHINE TOOLS Filed Aug. 20, 1934 3 Sheets-Sheet 3 {R p Q ZwNTOR.

j BY MM ATTORN E Y5 Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE AUXILIARY POWER OPERATED DEVICE FOR MACHINE TOOLS Application August 20, 1934, Serial No. 740,619 4 Claims. (CI. 90-21) This invention relates to mechanism for eflecting and controlling the movement or operation, at comparatively high speed, of movable elements on machine tools and the like. More particularly the invention relates to a detachable auxiliary power operated unit which may be readily applied to movable elements of standard machine tools, such as work tools, and is so connected with the operating mechanism thereof that movement of the table at high speed is effected through the medium of power, and under the direct control of the operator.

An object of the invention is a device of the kind referred to so constructed that it may be readily and easily applied to the work tables of machine tools now in use, and also a device which, in some instances, is interchangeable with the usual hand crank, or one of the usual hand cranks for operating the feed screw.

A further object of the invention is such a device so constructed that the operating parts and power unit are self contained and accordingly operate with the maximum of eiiiciency, and also a unitary device which is easily applied to the machine tool.

A further object of the invention is a device of the class referred to by which very small or maximum movements of the table of the machine tool are quickly and accurately efiected without any appreciable effort, or consumption of time, on the part of the operator.

The invention consists in the novel features and in the combinations and constructions herein after set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

Figure 1 isa partial perspective view of a machine tool with the power unit secured to the table thereof.

Figure 2 is a longitudinal, sectional view of the power unit together with a contiguous portion of the work table to which it is attached.

Figure 3 is an end elevation of the power unit,

looking to the left Figure 2.

Figure 4 is an end elevation, partly in section, looking to the right Figure 2.

l designates generally a machine tool, and as shown in Figure 1 of the drawings consists of a milling machine with the usual work table I I supported on a saddle I! which, in turn, is carried by a knee l3 which is movable vertically. The saddle I2 is movable on the knee l3 toward and from the body of the machine, or the cutting several hundred pounds.

tool II. The table II is movable at right angles to the movement of the saddle II, which move ment is effected by rotation of the screw 15 carried by the table and threading into a suitable nut, not shown, carried in the saddle l2. 5

Suitable means is provided whereby the operator may efiect rotation of the screw l5 and slow movement of the table II by means of the'power actuating the cutting tool 14.

, I6 designates a piece of work secured to the 10 table I I. As indicated in Figure 1, the table been moved to the left and the work It passed in engagement with the cutter l4, and the table returned to the right. If further milling of the work is required, the knee l3 may be elevated, or the saddle l2 moved inwardly toward the cutter, and the table II again moved to the left and another cut taken on the work IS. The construction and operation of the milling machine above described forms no part of this invention per se. This invention has to do with a power operated device for effecting movement of the table at high speed. Uusually, the screw I5 is provided at one, or both, ends with a suitable crank, or hand wheel, whereby the screw may be rotated manually. It is to be understood that when the screw I5 is operated by the power feed of the machine tool, it is operated at a comparatively slow speed, as it is necessary to pass the work 30,

I6 very slowly into engagement with the cutter l4. After a out has been taken, the operator releases the power feed on the screw l5 and returns the table by hand manipulation of the screw IS in order to avoid the delay that would result in reversing the power application to the lead screw IS. The operator then removes the work l6 and secures another piece on the table and rotates the screw by hand until the work is brought into close proximity to the cutter [4, then the regular power feed is connected to rotate the screw 15 to move the table and work past the cutter.

On large machine tools the work tables weigh Often the work itself will weigh one hundred or more pounds, all of which results in the necessity of the applica tion of a considerableamount of energy 'on the part of the operator to move the table and work by hand. Also, a considerable amount of time is consumed by the operator in walking to the end of the table and turning the screw IE to return the table to its initial position after having passed the work by the cutter. Further time is consumed by the operator in again walking to the end of the table and rotating the screw it to bring the work into close proximity to the cutter. Obviously, where the machine is used constantly, as on production work, a considerable amount of unproductive time is thus consumed, and in addition the operator becomes fatigued and the production of the machine decreases during the working day.

The general object of this invention is a small compact, rigid power unit manually controlled by the operator, and in operation obviates the necessity of the operator manually returning the table to loading position after a out has been taken, and also moving the table with the work in proximity to the cutter preparatory to taking a new cut. Obviously, the saving of time thus eifected is very appreciable.

The invention consists generally of a power unit provided with'means for connection to the operating screw of the work table, and a bracket for attaching the power unit to the work table. The power unit includes an electric motor, a driven shaft connected to the operating screw of the table, and motion transmitting means between the motor shaft and the driven shaft, and also includes a unitary attachment in which the mechanism includes an electric motor, motion transmitting means operated by the motor including an overload clutch and a coupling for connecting the motion transmitting mechanism to the feed screw, all of which parts are all enclosed within a bracket in the form of a housing which is readily attachable to the machine tool, the housing protecting the mechanism within it against dust, chips, etc.

20 designates generally the power unit. As here shown, it includes a housing 2| which is provided with a cylindrical bore 22 which is closed at the inner end by a partition 23, and on the opposite or outer end by a detachable cap or cover 24 secured to the housing by screws 23. The bore 22 is machined to receive the fleld laminations 23 of an electric motor, here shown as an induction motor provided with windings 21 so formed as to effect either forward or reverse rotation of the rotor and motor shaft 23. The motor shaft 23 is suspended in suitable antifriction bearings 29 located in the partition 23 and end cap 24 with the shaft extending through the partition 23, and is provided with a pinion gear 30 suitably keyed thereto. The housing 2|, as here shown, is provided with an integral depending portion 3I in which suitable antifriction bearings 32 are mounted in spaced apart relationship, and which support a driven shaft 33.

34 designates a dust cap which acts as a closure for the outer end of the bore of the depending portion. The driven shaft- 33 extends paralilel to the motor shaft 23 and projects inwardly beyond the plane of the partition 23. A gear 33 is mounted upon the projecting portion of the shaft 33 and meshes with the pinion gear 30 on the motor shaft 23. The gear 33 may be formed integral with the shaft 33, or keyed thereto in any suitable manner. However, I have found it desirable to provide a yielding connection between the motor shaft 23 and the driven shaft 33. As here shown, the projecting portion of the shaft 33 is formed, or provided, with a disk 33 which is integral with the shaft 33, or secured thereto, and rotatable therewith. A second disk 31 is slidabiy-mounted upon the shaft 33 and keyed thereto as at 33. The disk 31 is provided with a short hub portion 33, and the gear 33 is provided with a disk web portion 43 which is arranged between the disks 33, 31,

and is provided with a' central bore to receive the hub 33 of the disk 31.

The shaft 33 is threaded, as at 4|, to receive an adjustment nut 42 which is provided with a suitable locking means as at 43. A spring washer 44 is inserted between the nut 42 and the slidable disk 31. Obviously, the frictional contact between the gear 33 and the disks 33, 31, may be varied by adjusting the nut 42.

The driven shaft 33 is connected to the outer end of the table screw i3. As here shown, the shaft 33 is provided with a suitable connection 45 being secured to the shaft 33 by a pin 43.

The outer end of the connection 43 is provided with a square aperture to receive the squared end of the screw I 3. It is to be understood that the projecting ends of the screw II are usually squared to receive the crank, or hand wheel, for manually manipulating the screw, in which instance, the hand wheel, or crank, is removed from the screw and is replaced by the connection 43. However, the connection 43 may be secured, in any suitable manner, to the end of the screw it. The table screw I3 is supported by suitable bearing brackets 41 which are secured to the ends of the work table II.

Obviously, upon rotation of the motor shaft 23, such rotation is transmitted to the screw l3, through the gears 33. 33, disks 33, 31, driven shaft 33, and connection 43. The structure thus far described may be designated as the power unit of the device. This power unit is secured to the end of the work table II by means of a suitable support or bracket 43. The bracket 43 is secured to the work table by screws 43. The housing is provided with a rectangular flange 33 which is secured to the bracket by screws II.

The structure thus far described consists of a power unit which is entirely self contained and which, by means of the bracket 43, may be readily attached to the work table of any machine tool without necessitating the adjustment or fitting of any of the parts of the power unit and accordingly, eliminating the possibility of getting the working parts of the power unit out of alinement, and decreasing the eiiiciency thereof. The power unit described is suitable for practically all types of machine tools. The only adjustment necessaryin attaching the device to the machine tool consists in fitting the bracket 43 to the machine. Generally, there is little variation in the construction of work tables on a particular class of machine tools, such as milling machines. However, if there be any variation, for example, a variation in the distance between the center of the screw l3 and the surface of the table Ii, the same is compensated for by machining more or less off from the inner end of the bracket 43. However, no attachment is necessary in the power unit per so. This feature is of importance inasmuch as it permits ordinary mechanics to quickly attach the device in proper manner to the work table, and without tampering in any way with the construction of the power unit.

The housing 2| is also provided with a depending arouate portion 32 which serves as a housing for the gear 33 and the associated clutch mechanism.

I have found, in some instances, that it is desirable to provide the device with means controlled by the operator whereby he may instantaneously stop any movement of the work tsbl Ii. Such a means is desirable where the opera tor wishes to quickly move the table and work up to close proximity to the cutter preparatory housing 2|, and the other end is secured to the inner end of a lever 58, as at 59. The lever 58 is pivoted in the front side of the housing as at 60, and projects outwardly through the side of the housing whereit may be conveniently manipulated by the operator. When it is desired to instantly stop movement of the table in either direction, the operator pulls upwardly on the lever 58 which draws the brake band 58 into engagement with the disk 55.

As previously stated, the' winding 21 of the motor is such as to effect reverse rotation of the shaft 28. The motor is controlled by a suitable switch 66 conveniently located within easy reach of the operator. As her'e shown, it is secured to the front side of the saddle l2 of the milling machine. The switch 66, here shown, is provided with a pair of manuals B1, 68. Operation of one manual causes the motor to operate in one direction and move the table, and operation of the other manual causes the motor to operate in reverse direction and move the table in the opposite direction. Any suitable reversing switch may be employed. The operating circuit for the motor, as here shown, is taken from the switch box 10, through cable II, to the reversing switch 66 and thence, through cable 12 to the motor windings 21.

In use, the friction clutch of this device is so adjusted by the nut 42 that it has just enough tension to move the table without slipping. If the power feed is connected to the screw l5, or if the table is so moved by the device as to jar the work against the cutter the friction clutch will slip and not damage the machine, or stall the motor, and thereby seriously damage the windings of the motor.

What I claim is:

1. The combination of a machine tool having a movable work table with a feed screw operable to move said table and an auxiliary power operated device for operating said screw, said device including a housing formed with,a motor compartment, a motor mounted in said compartment and having its rotor shaft extending through one end thereof, a driven shaft rotatably mounted in said housing, motion transmitting means connecting the motor shaft and the driven shaft including an overload clutch mechanism, a bracket detachably secured to one end of the table, said bracket acting as a support for the housing, and means connecting the driv-' en shaft to the feed screw of the table.

2. The combination of a machine tool having a movable table with a feed screw for effecting miovement of the table, and an auxiliary power operated device for operating the feed screw, said device including an integral housing, a motor mounted in said housing, a driven shaft mounted in said housing and operably connected with the feed screw of the table, gearing arranged between the motor shaft and the driven shaft for transmitting motion from the motor shaft to the driven shaft, a drum secured to the motor shaft and brake mechanism coacting with said drum, said brake mechanism being manually oper'able from the outside of the housing.

3. A unitary power operated appliance for a machine tool having a feed screw, said appliance comprising a casing provided with means for attachment to the machine tool, a motor mounted in the casing, a driven shaft rotatably mounted in the casing and arranged to come in axial alinement with the feed screw, and gearing arranged in the casing and connecting the motor and the driven shaft, said gearing including an overload clutch, and means for coupling the driven shaft to the feedscrew, and a manually operable brake mechanism coacting with the rotor.

4. An auxiliary unitary power operated device for a machine tool having a work table and a feed screw for operating said table, said device comprising a casing, a nalied in said casing, a bracket detachably supporting said casing on the work table with said shaft arranged in axial alinement with the table feed screw, the inner end of said shaft being coupled to the projecting end of the feed screw to effect rotation of said screw upon rotation of the shaft, a motor mounted in the casing, gearing arranged in the casing and operatively connecting the rotor shaft of said motor and said first mentioned shaft, and an overload clutch associated with said first mentioned shaft and operable when the torque between the rotor shaft of the motor and the feed screw reaches a predetermined value to permit relative rotative movement between the rotor shaft and the feed screw.

ARTHUR H. EMMONS.

shaft rotatably jour-- 

